1. Field of the Invention
The present invention relates to a process for elementary analysis by optical emission spectrometry on plasma produced by a laser in the presence of argon. It applies to the in situ checking and inspection of samples and the characterization of machined parts. It is more particularly usable in the nuclear industry for the inspection of radioactive materials.
2. Discussion of the Background
It is known to measure the elementary concentrations of elements by a spectrochemical analysis using the emission radiation of a plasma produced by laser. This analytical method is based on a laser ablation, i.e. a tearing away of material under the effect of high heat levels.
The process for analysis by optical emission spectrometry on plasma produced by a laser uses such a laser ablation. It consists of focussing on the surface of the solid to be studied a pulsed laser beam having a high peak power (typically a few GW/cm.sup.2) so as to produce a plasma constituted by chemical elements present in the first microns of the surface. This plasma emits a light radiation, the analysis of the atomic lines thereof making it possible to obtain information on the concentration of the different elements in the solid.
However, such a process does not have a very high sensitivity which, for certain analytical cases, is completely inadequate. In addition, it is known that certain gases constitute a more favourable atmosphere for spectral analyses than the natural atmosphere (i.e. air).
A procedure for improving the intensity of the lines during spectral analyses and therefore for improving the accuracy of the measurements, consists of placing the sample to be analysed in a closed container filled with a gas and more particularly argon.
According to this procedure the measurements are performed in a confined atmosphere, so that it can only be carried out in the laboratory.